The present invention relates generally to underwater face masks and, more particularly, to underwater diving masks having eyepieces or lenses mounted on a flexible gasket.
In the past, a variety of underwater face masks have been used for sporting and other activities such as skin and scuba diving. Early underwater face masks typically had several common features, including a contiguous air space shared by the diver""s nose and eyes, generally flat, glass or plastic windows, eyepieces or ports fixed approximately perpendicularly to the wearer""s straight-ahead viewing axis, and a flexible rubber or plastic support structure for holding the ports in position and trapping an air pocket against the wearer""s face. A contiguous air pocket over both the wearer""s nose and eyes, as opposed to a mask covering the eyes only, allows for equalizing pressure inside the mask with ambient water pressure as the wearer ascends and descends in the water. Such equalization is necessary to avoid injury to the wearer.
Such conventional flat-window face masks share a variety of shortcomings. The windows or eyepieces of conventional flat-window masks must be supported out from the face. Above and below water, the wearer""s horizontal and vertical fields of view are severely limited by the flexible rubber or plastic structures providing such support, thereby creating a sense of xe2x80x9ctunnel visionxe2x80x9d and a closed-in, claustrophobic feeling. Above water, conventional flat-window masks provide no more than a 140 degree horizontal by 90 degree vertical field of view. Below water, because of the refraction-induced magnification distortion of an air-water viewing system, discussed more fully hereinbelow, this field of view is effectively reduced to approximately 105 degrees horizontal by 67.5 degrees vertical.
Additionally, conventional flat-window masks suffer quite significant magnification-distortion problems from the difference in refractive indices between water and air. Specifically, objects viewed on an axis perpendicular to the window appear approximately 33% larger and 25% closer than they actually are. The magnification-distortion of objects viewed off-axis is even larger.
Further, conventional flat-window masks create a significant amount of hydrodynamic drag and present a significant risk of slipping off the wearer""s face if hit by an unanticipated or oblique-angle wave or current.
These and other flat-window mask problems have attempted to be overcome, with less than satisfactory results, by spherically-shaped eyepieces or lenses used for underwater masks. For example, U.S. Pat. Nos. 3,899,244, issued to Mulder on Aug. 12, 1975, and 3,672,270, issued to Hagen on Jun. 27, 1972, disclose underwater masks that use built-in corrective lenses in addition to spherically-shaped lenses to improve viewing under water. As such, these masks do not provide optimum viewing characteristics under water without the use of additional corrective lenses. Other single and multiple lens systems used for underwater face masks that do not provide optimum viewing conditions are disclosed in U.S. Pat. Nos. 3,944,345, issued to Decorato on Mar. 16, 1976; 3,040,616, issued to Simpson on Jun. 26, 962; 2,088,262, issued to Grano on Jul. 27, 1937; 2,928,097, issued to Neufeld on Mar. 15, 1960; and 1,742,412, issued to O""Flanagan on Jan. 7, 1930.
U.S. Pat. No. 4,607,398, issued to Faulconer on Aug. 26, 1986, discloses a strap and retainer used for a diver""s mask. U.S. Pat. No. 3,051,957, issued to Chan on Sep. 4, 1962, describes a diving mask having a supporting device used to hold the eyeglasses of a diver. In addition, U.S. Pat. No. 4,856,120, issued to Hart on Aug. 15, 1989, describes a purge valve used for a diving mask and a deflector attached to the mask and used to channel air bubbles expelled during purging to the sides of the mask. Another purge valve used for a diver""s mask is disclosed in U.S. Pat. No. 4,241,898, issued to Segrest on Dec. 30, 1980.
Accordingly, it is an object of this invention to provide a diving mask which furnishes improved viewing characteristics under water.
It is another object of this invention to provide a diving mask which furnishes improved viewing characteristics under water, and may be used under water by divers who do not have to wear contact lenses or eyeglasses to correct eyesight when not under water.
It is still another object of this invention to provide a diving mask which furnishes improved viewing characteristics under water, and may be used under water by divers while not wearing contact lenses which correct eyesight above water.
It is still another object of this invention to provide a diving mask which furnishes improved viewing characteristics under water, and may be used under water by divers while wearing contact lenses which correct eyesight above water.
It is still another object of this invention to provide a diving mask which may be used both above and under water.
It is still another object of this invention to provide a diving mask which may be used both above and under water with additional corrective lenses if desired.
It is still another object of this invention to provide a diving mask which furnishes a secure seal between the mask and the wearer""s face.
It is still another object of this invention to provide a method of fabricating such a diving mask.
These and other objects and advantages are attained by a diving mask having hemispherically-shaped lenses mounted on a flexible gasket and fitted to the contours of a user""s face. Laser scanning or topographical mapping is used to determine the contours of a user""s face. The perimeter edges of the hemispherically-shaped lenses are then sized to fit the contours of the face. As a result, the spherical center of each of the hemispherically-shaped lenses substantially coincides with the optical nodal point of one of the user""s eyes. This improvement virtually eliminates the phenomenon of underwater magnification-distortion caused by the difference in refractive indices of water and air. Improved horizontal and vertical fields of view are also provided by the hemispherically-shaped lenses. A secure seal is provided between the diving mask and a user""s face by the flexible gasket.
Another embodiment of the diving mask is provided having a standard pair of hemispherically-shaped lenses mounted on a contoured portion of the mask which is fitted to the contours of a user""s face. The contoured portion is mounted on a flexible gasket.
In still another embodiment of the diving mask, the hemispherically-shaped lenses are designed so that the spherical center of curvature of each of the lenses substantially coincides with the center of rotation of one of a user""s eyes.
In still another embodiment of the diving mask, a shaft is mounted on the hemispherically-shaped lenses. The shaft is coupled to a pair of retractable corrective lenses, and may be used to lower the corrective lenses to a position in front of a user""s eyes and to raise the lenses to a position above the eyes. The corrective lenses may be used by near- and far-sighted users.
In still another embodiment of the diving mask, the hemispherically-shaped lenses are mounted on a support portion having a peripheral flange. The support portion, in turn, is mounted on a flexible gasket of selected size. The diving mask may have at least one purge valve in the support portion.
In still another embodiment, a diving mask is provided having a purge valve in at least one of the hemispherically-shaped lenses. The purge valve is located at the front and bottom of the lens and in an area used to collect water which has leaked into the mask. The collecting area is angled to facilitate expelling water from the diving mask through the purge valve so that exhaust bubbles pass toward the back of the mask, away from the field of vision of a diver.
In still another embodiment, the diving mask is provided with a bottom lens which facilitates drainage of water from the mask. The bottom lens may also be used for viewing both above and below the water. The diving mask may also have an additional lens mounted inside the mask which may be used by either nearsighted or farsighted divers. A member may be joined to the additional lens in order to provide trapped dry-air volume inside the mask.
In still another embodiment of the diving mask, a baffle may be used with textured or coated surfaces in order to provide a translucent member for the purpose of eliminating double vision. Also, the ends of the lenses may be bent or formed inwardly toward a diver""s face in order to provide a reduced air volume inside the mask.
In still another embodiment of the mask, hemispherically-shaped meniscus lenses are used to provide reduced weight and a reduced air volume inside the mask. The curvatures of the inner and outer surfaces of the meniscus lenses are chosen to produce an effective zero diopter value under water. The spherical centers of curvature of the meniscus lenses are located beneath the centers of a diver""s eye in order to reduce the weight of the mask and to improve drainage.
In still another embodiment of the diving mask, a perimeter clamp is used to clamp a conventional face seal to a support portion of the mask. Integral housings may be formed in the support portion for purge valves. Integral housings for the purge valve may also be formed in the perimeter clamp. A purge valve is provided for each lens.
The various features of the present invention will be best understood together with further objects and advantages by reference to the following description of the preferred embodiments taken in conjunction with the accompanying drawings.